"It's appalling to know executives at major networks like NBC and CNN who have donated to Democrats and Hillary Clinton have taken it upon themselves to be Hillary Clinton's campaign operatives," Priebus said in a statement.

NBC has announced plans to air a four-hour miniseries about the former first lady, senator and U.S. secretary of state entitled "Hillary," which, the network says, will track "Clinton's life as a wife, mother, politician, and cabinet member," starting in 1998.

CNN is planning a documentary from director Charles Ferguson, who won an Oscar in 2011 for his movie "Inside Job," which he described as chronicling "the systemic corruption of the United States by the financial services industry."

In the letters, Priebus said the decision to produce the shows was unfair, both to Clinton's potential Democratic rivals — who he said could include Vice President Joe Biden, Govs. Martin O'Malley of Maryland, Andrew Cuomo of New York and John Hickenlooper of Colorado, and Minnesota Sen. Amy Klobuchar — and to the eventual GOP pick, should Clinton win the Democratic primary.

In his letter to Greenblatt, Priebus detailed more than $2 million in campaign donations to Democrats from NBC executives and employees. "NBC cannot purport to be a neutral party in American politics, and the credibility of NBC News, already damaged by the partisanship of MSNBC, will be further undermined by the actions of NBC Universal executives who have taken it upon themselves to produce an extended commercial for Secretary Clinton's nascent campaign," he added.

He told Zucker, "Secretary Clinton has been in the public eye for well over two decades, so you certainly cannot claim that a documentary about her political career is any sort of public service or eye-opening journalism on an unknown individual. Quite the opposite is true: it would be most accurately described as an in-kind donation."

Priebus said the networks' "actions to promote Secretary Clinton are disturbing and disappointing."

He added, "I hope Americans will question the credibility of these networks and that NBC and CNN will reconsider their partisan actions and cancel these political ads masked as unbiased entertainment," he said.

"If they have not agreed to pull this programming prior to the start of the [Republican National Committee's] Summer Meeting on August 14, I will seek a binding vote stating that the RNC will neither partner with these networks in 2016 primary debates nor sanction primary debates they sponsor."

Republican National Committee Chairman Reince Priebus on Monday gave two television networks less than two weeks to pull major projects on the life of Hillary Clinton. If they don't, Priebus says he will work to stop both NBC and CNN from airing Republican primary debates...